1. Field of the Invention:
The present invention relates to a method and device for separating trimming losses of products formed from sheets and more particularly a method and device for blanking star-shaped trimming losses or scraps formed between adjacent formed products when a plurality of products are formed from a synthetic resin sheet to thereby completely separate the star-shaped scraps from the formed products.
2. Description of the Prior Art:
A plurality of formed products such as vessels, trays and the like having the same shape are formed from a sheet of a synthetic resin such as foamed polystyrene. A thermal forming process is used such as a vacuum forming process, a pressurized chamber forming process, a pressing process or the like. A trimming process is used to separate the formed products from each other.
In trimming the formed products, Thomson cutting blades or the like are used to define shearing lines around the outer peripheries of the formed products. Parts of the shearing lines are not completely cut and are left as connecting parts so that the formed products are not separated from each other. Thereafter, only the formed products are blanked by a mechanical press so that frame-shaped loss parts or scrap around the blanked products and the products themselves are separated from each other and the products thus formed are recovered.
When the outer peripheral continuous frame-shaped trimming-loss portions or scraps of the sheet are securely clamped by suitable means, it becomes relatively simple to separate the formed products from the frame-shaped scraps. Meanwhile, star-shaped trimming losses or scraps are left on portions of the sheet where the corners of the formed products are adjacent to each other. Many star-shaped scraps are separated from each other and are extremely small in size thus, a problem arises in that it is difficult to hold or clamp each star-shaped scrap and consequently it is difficult to separate them from the formed products.
In order to overcome the above-mentioned problem, Laid-Open Japanese patent application Ser. No. 61-7920 has disclosed a method in which after the formed products are trimmed, the star-shaped scraps are blanked and removed and then the formed products are separated from their outer peripheral frame-shaped scraps and recovered. In this method, in order to separate and remove a large number of star-shaped scraps, knock pins are pressed against the star-shaped scraps and are received by sheet-like jigs so that the star-shaped scraps are blanked and separated from the formed products.
However, according to the above-mentioned method, when the star-shaped scraps are blanked by the knock pins, static electricity is produced and the trimming scraps may adhere to the formed products such as food containers, trays or the like. This phenomenon is one of the most serious defects because in many cases, food is contained in the formed products.
Furthermore, in the case of the device of the type disclosed in the above-mentioned Laid-Open Japanese patent application Ser. No. 61-7920, the knock pins are pressed against the upright plate-shaped jigs. As a result, the separated star-shaped scraps are inclined so that they do not smoothly drop in the receiving holes. This phenomenon is also the cause of the adhesion of the star-shaped scraps to the formed products.